Using Mask/2d Image To Drive Vertices That 3dreplicate Targets

i hop that topic is not too confusing.
basicly i have a pice of geomatry. (for example a cylinder) and i want to place a sphere at certain versices of this cylinder. And the way i would like to controle which vertice recieves a sphere is by a 2D map.
If that could be also done with a particle system that would a even better. or a image emitter.
I just need to partiles to be positioned in a equel distanzes form each other in a grid like fashion. and follow a 3D shape. and i have to be able to controll the position with a map.